Openssl Key

  1. Openssl Key Iv
  2. Generate Rsa Key Openssl
  3. Openssl Key Encryption
  4. Openssl Key Generation


What is OpenSSL? OpenSSL is a very useful open-source command-line toolkit for working with X.509 certificates, certificate signing requests (CSRs), and cryptographic keys. If you are using a UNIX variant like Linux or macOS, OpenSSL is probably already installed on your computer. # openssl req -new -newkey rsa:2048 -nodes -keyout ban27.key -out ban27.csr In this example we are creating a private key ( ban27.key ) using RSA algorithm and 2048 bit size. Next we will use this ban27.key to generate our CSR ( ban27.csr ). The JOSE standard recommends a minimum RSA key size of 2048 bits. To generate a 2048-bit RSA private + public key pair for use in RSxxx and PSxxx signatures: openssl genrsa 2048 -out rsa-2048bit-key-pair.pem.

This plugin is part of the community.crypto collection (version 1.6.1).

To install it use: ansible-galaxycollectioninstallcommunity.crypto.

To use it in a playbook, specify: community.crypto.openssl_privatekey.

  • Keys are generated in PEM format.

  • One can generate RSA, DSA, ECC or EdDSA private keys.

  • Please note that the module regenerates private keys if they don’t match the module’s options. In particular, if you provide another passphrase (or specify none), change the keysize, etc., the private key will be regenerated. If you are concerned that this could overwrite your private key, consider using the backup option.

  • The default mode for the private key file will be 0600 if mode is not explicitly set.

  • The module can use the cryptography Python library, or the pyOpenSSL Python library. By default, it tries to detect which one is available. This can be overridden with the select_crypto_backend option. Please note that the PyOpenSSL backend was deprecated in Ansible 2.9 and will be removed in community.crypto 2.0.0.

  • This module allows one to (re)generate OpenSSL private keys.

The below requirements are needed on the host that executes this module.

  • Either cryptography >= 1.2.3 (older versions might work as well)

  • Or pyOpenSSL

The attributes the resulting file or directory should have.
To get supported flags look at the man page for chattr on the target system.
This string should contain the attributes in the same order as the one displayed by lsattr.
The = operator is assumed as default, otherwise + or - operators need to be included in the string.
  • no
  • yes
Create a backup file including a timestamp so you can get the original private key back if you overwrote it with a new one by accident.
The cipher to encrypt the private key. (Valid values can be found by running `openssl list -cipher-algorithms` or `openssl list-cipher-algorithms`, depending on your OpenSSL version.)
  • secp224r1
  • secp256k1
  • secp256r1
  • secp384r1
  • secp521r1
  • secp192r1
  • brainpoolP256r1
  • brainpoolP384r1
  • brainpoolP512r1
  • sect163k1
  • sect163r2
  • sect233k1
  • sect233r1
  • sect283k1
  • sect283r1
  • sect409k1
  • sect409r1
  • sect571k1
  • sect571r1
Note that not all curves are supported by all versions of cryptography.
For maximal interoperability, secp384r1 or secp256r1 should be used.
We use the curve names as defined in the IANA registry for TLS.
Please note that all curves except secp224r1, secp256k1, secp256r1, secp384r1 and secp521r1 are discouraged for new private keys.
  • yes
Should the key be regenerated even if it already exists.
  • pkcs1
  • pkcs8
  • raw
  • auto
  • auto_ignore
Determines which format the private key is written in. By default, PKCS1 (traditional OpenSSL format) is used for all keys which support it. Please note that not every key can be exported in any format.
The value auto selects a fromat based on the key format. The value auto_ignore does the same, but for existing private key files, it will not force a regenerate when its format is not the automatically selected one for generation.
Note that if the format for an existing private key mismatches, the key is regenerated by default. To change this behavior, use the format_mismatch option.
The format option is only supported by the cryptography backend. The pyopenssl backend will fail if a value different from auto_ignore is used.
  • regenerate
  • convert
Determines behavior of the module if the format of a private key does not match the expected format, but all other parameters are as expected.
If set to regenerate (default), generates a new private key.
If set to convert, the key will be converted to the new format instead.
Name of the group that should own the file/directory, as would be fed to chown.
The permissions the resulting file or directory should have.
For those used to /usr/bin/chmod remember that modes are actually octal numbers. You must either add a leading zero so that Ansible's YAML parser knows it is an octal number (like 0644 or 01777) or quote it (like '644' or '1777') so Ansible receives a string and can do its own conversion from string into number.
Giving Ansible a number without following one of these rules will end up with a decimal number which will have unexpected results.
As of Ansible 1.8, the mode may be specified as a symbolic mode (for example, u+rwx or u=rw,g=r,o=r).
Name of the user that should own the file/directory, as would be fed to chown.
Name of the file in which the generated TLS/SSL private key will be written. It will have 0600 mode if mode is not explicitly set.
  • never
  • fail
  • partial_idempotence
  • full_idempotence
  • always
Allows to configure in which situations the module is allowed to regenerate private keys. The module will always generate a new key if the destination file does not exist.
By default, the key will be regenerated when it doesn't match the module's options, except when the key cannot be read or the passphrase does not match. Please note that this changed for Ansible 2.10. For Ansible 2.9, the behavior was as if full_idempotence is specified.
If set to never, the module will fail if the key cannot be read or the passphrase isn't matching, and will never regenerate an existing key.
If set to fail, the module will fail if the key does not correspond to the module's options.
If set to partial_idempotence, the key will be regenerated if it does not conform to the module's options. The key is not regenerated if it cannot be read (broken file), the key is protected by an unknown passphrase, or when they key is not protected by a passphrase, but a passphrase is specified.
If set to full_idempotence, the key will be regenerated if it does not conform to the module's options. This is also the case if the key cannot be read (broken file), the key is protected by an unknown passphrase, or when they key is not protected by a passphrase, but a passphrase is specified. Make sure you have a backup when using this option!
If set to always, the module will always regenerate the key. This is equivalent to setting force to yes.
Note that if format_mismatch is set to convert and everything matches except the format, the key will always be converted, except if regenerate is set to always.
  • no
  • yes
If set to yes, will return the (current or generated) private key's content as privatekey.
Note that especially if the private key is not encrypted, you have to make sure that the returned value is treated appropriately and not accidentally written to logs etc.! Use with care!
Use Ansible's no_log task option to avoid the output being shown. See also
  • cryptography
  • pyopenssl
Determines which crypto backend to use.
The default choice is auto, which tries to use cryptography if available, and falls back to pyopenssl.
If set to pyopenssl, will try to use the pyOpenSSL library.
If set to cryptography, will try to use the cryptography library.
Please note that the pyopenssl backend has been deprecated in Ansible 2.9, and will be removed in community.crypto 2.0.0. From that point on, only the cryptography backend will be available.
This is the MLS/MCS attribute, sometimes known as the range.
When set to _default, it will use the level portion of the policy if available.
When set to _default, it will use the role portion of the policy if available.
When set to _default, it will use the type portion of the policy if available.
By default it uses the system policy, where applicable.
When set to _default, it will use the user portion of the policy if available.
Size (in bits) of the TLS/SSL key to generate.
  • absent
Whether the private key should exist or not, taking action if the state is different from what is stated.
  • DSA
  • ECC
  • Ed25519
  • Ed448
  • X25519
  • X448
The algorithm used to generate the TLS/SSL private key.
Note that ECC, X25519, X448, Ed25519 and Ed448 require the cryptography backend. X25519 needs cryptography 2.5 or newer, while X448, Ed25519 and Ed448 require cryptography 2.6 or newer. For ECC, the minimal cryptography version required depends on the curve option.
  • no
  • yes
Influence when to use atomic operation to prevent data corruption or inconsistent reads from the target file.
By default this module uses atomic operations to prevent data corruption or inconsistent reads from the target files, but sometimes systems are configured or just broken in ways that prevent this. One example is docker mounted files, which cannot be updated atomically from inside the container and can only be written in an unsafe manner.
This option allows Ansible to fall back to unsafe methods of updating files when atomic operations fail (however, it doesn't force Ansible to perform unsafe writes).
IMPORTANT! Unsafe writes are subject to race conditions and can lead to data corruption.

See also

Openssl Key

The official documentation on the community.crypto.openssl_privatekey_pipe module.


The official documentation on the community.crypto.openssl_privatekey_info module.


The official documentation on the community.crypto.x509_certificate module.


The official documentation on the community.crypto.x509_certificate_pipe module.


The official documentation on the community.crypto.openssl_csr module.


The official documentation on the community.crypto.openssl_csr_pipe module.


The official documentation on the community.crypto.openssl_dhparam module.


The official documentation on the community.crypto.openssl_pkcs12 module.


The official documentation on the community.crypto.openssl_publickey module.

Common return values are documented here, the following are the fields unique to this module:

changed and if backup is yes
curvechanged or success, and type is ECC
Elliptic curve used to generate the TLS/SSL private key.

changed or success
fingerprintchanged or success
The fingerprint of the public key. Fingerprint will be generated for each hashlib.algorithms available.
The PyOpenSSL backend requires PyOpenSSL >= 16.0 for meaningful output.

{'md5': '84:75:71:72:8d:04:b5:6c:4d:37:6d:66:83:f5:4c:29', 'sha1': '51:cc:7c:68:5d:eb:41:43:88:7e:1a:ae:c7:f8:24:72:ee:71:f6:10', 'sha224': 'b1:19:a6:6c:14:ac:33:1d:ed:18:50:d3:06:5c:b2:32:91:f1:f1:52:8c:cb:d5:75:e9:f5:9b:46', 'sha256': '41:ab:c7:cb:d5:5f:30:60:46:99:ac:d4:00:70:cf:a1:76:4f:24:5d:10:24:57:5d:51:6e:09:97:df:2f:de:c7', 'sha384': '85:39:50:4e:de:d9:19:33:40:70:ae:10:ab:59:24:19:51:c3:a2:e4:0b:1c:b1:6e:dd:b3:0c:d9:9e:6a:46:af:da:18:f8:ef:ae:2e:c0:9a:75:2c:9b:b3:0f:3a:5f:3d', 'sha512': 'fd:ed:5e:39:48:5f:9f:fe:7f:25:06:3f:79:08:cd:ee:a5:e7:b3:3d:13:82:87:1f:84:e1:f5:c7:28:77:53:94:86:56:38:69:f0:d9:35:22:01:1e:a6:60:...:0f:9b'}
if state is present and return_content is yes
The (current or generated) private key's content.
Will be Base64-encoded if the key is in raw format.

changed or success
typechanged or success
Algorithm used to generate the TLS/SSL private key.



  • Yanis Guenane (@Spredzy)

  • Felix Fontein (@felixfontein)

Skip to main content

Encrypt and decrypt files to public keys via the OpenSSL Command Line

Published: 25-10-2018 Author: Remy van Elst Text only version of this article

❗ This post is over two years old. It may no longer be up to date. Opinions may have changed.

Table of Contents

This small tutorial will show you how to use the openssl command line to encryptand decrypt a file using a public key. We will first generate a random key,encrypt that random key against the public key of the other person and use thatrandom key to encrypt the actual file with using symmetric encryption.

Consider sponsoring me on Github. It means the world to me if you show your appreciation and you'll help pay the server costs.
You can also sponsor me by getting a Digital Ocean VPS. With this referral link you'll get $100 credit for 60 days.

Because of how the RSA algorithm works it is not possible to encrypt largefiles. If you create a key of n bits, then the file you want to encrypt mustnot larger than (n minus 11) bits. The most effective use of RSA crypto is toencrypt a random generated password, then encrypt the file with the passwordusing symmetric crypto. If the file is larger then the key size the encryptioncommand will fail:

We generate a random file and use that as the key to encrypt the large file withsymmetric crypto. That random file acts as the password so to say. We encryptthe large file with the small password file as password. Then we send theencrypted file and the encrypted key to the other party and then can decrypt thekey with their public key, the use that key to decrypt the large file.

The following commands are relevant when you work with RSA keys:

  • openssl genrsa: Generates an RSA private keys.
  • openssl rsa: Manage RSA private keys (includes generating a public key from it).
  • openssl rsautl: Encrypt and decrypt files with RSA keys.

Openssl Key Iv

The key is just a string of random bytes. We use a base64 encoded string of 128bytes, which is 175 characters. Since 175 characters is 1400 bits, even a smallRSA key will be able to encrypt it.

Get the public key

Let the other party send you a certificate or their public key. If they send toa certificate you can extract the public key using this command:

Generate the random password file

Use the following command to generate the random key:

Do this every time you encrypt a file. Use a new key every time!

Update 25-10-2018

Generate Rsa Key Openssl

The key format is HEX because the base64 format adds newlines. The -passargument later on only takes the first line of the file, so the full key is notused. (Thanks Ken Larson for pointing this to me)

Encrypt the file with the random key

Use the following command to encrypt the large file with the random key:

The file size doesn't grows that much:

It's encrypted however:

Encrypt the random key with the public keyfile

Use the following command to encrypt the random keyfile with the other personspublic key:

You can safely send the key.bin.enc and the largefile.pdf.enc to the otherparty.

You might want to sign the two files with your public key as well.

Decrypt the random key with our private key file

Openssl Key Encryption

If you want to decrypt a file encrypted with this setup, use the followingcommand with your privte key (beloning to the pubkey the random key was cryptedto) to decrypt the random key:

This will result in the decrypted random key we encrypted the file in.

Decrypt the large file with the random key

Openssl Key Generation

Once you have the random key, you can decrypt the encrypted file with thedecrypted key:

This will result in the decrypted large file.

Tags: ca, certificate, decrypt, encrypt, openssl, pki, ssl, tls, tutorials